In recent years, suppression of energy consumption has been required in factories, offices (buildings), and homes. According to statistical data of the energy consumption, the proportion of the energy consumption in homes is relatively high in total energy consumption. Therefore, the suppression of the energy consumption in homes is an issue to be addressed. A technology of controlling energy in homes is called a “home energy management system” (HEMS). The HEMS implements measures for energy conservation including on/off control of electrical appliances such as an air conditioner, collection of logs of power consumption, and the like.
For example, Patent Document 1 discloses that a measuring unit is provided corresponding to each branch breaker in a home, the period of use and used electric energy of each appliance are measured by the measuring units, and measured values are stored in a use history memory unit in association with an appliance number of each appliance.